Prevention of off-flavors in radiationsterilized beef



United States Patent Ofice 3,093,489 PREVENTION OF OF -FLAVORS IN RADIATION STERILIZED BEEF Frank J. Alexander, Mount Prospect, and Louis A. Harriman, Chicago, Ill., assignors to the United States of America as represented by the Secretary of the Army No Drawing. Filed July 28, 1961, Ser. No. 127,750

' 7 Claims. (Cl. 99-217) This invention relates to a process of prevention of off-flavors in radiation sterilized beef, and more particularly to a process whereby the beef, which is susceptible to the development of cit-flavors as a result of radiation sterilization, is surrounded by a saline solution during irradiation. The resulting radiation-induced off-flavors are eluted from the beef and discarded with the saline solution.

It is known that beef can be sterilized by exposure to ionizing radiation, either of the beta-ray (high speed electrons) or gamma ray type, at a dosage in excess of about 1 megarad. The term megarad as used herein, refers to a dose of ionizing radiation which produces an energy absorption of 100x110 ergs per gram of irradiated substance. The term megarad has now replaced the term megarep, which latter term represents the quantity of ionizing radiation which produces energy absorption of 83 ergs per gram of tissue; thus, 1 rnegarep=.83 megarad, or 1 megarad=about 1.2 mega-reps.

It is equally known that the beef sterilized by this procedure acquires a peculiar disagreeable aroma, which has been called by the homely, but descriptive term wetdog aroma. 'I his off-flavor is very difficult to mask and greatly reduces the flavor acceptability of radiation sterilized beef. It has hereto-fore been proposed to overcome this drawback by reducing the sterilizing dosage substantially below 1 megarad, while protecting the beef by a gaseous chemical agent. Such a process does not result in true sterilization of the beef.

We have now discovered that the wet dog oifdlavors induced in beef can be eluted and removed from the beef by a saline solution, preferably of .85-4.25% strength, which is permitted to surround the beef during exposure to ionizing radiation at a sterilizing dosage in excess of 1 megarad. The solution and the eluted oif-flavors are discarded, prior to serving the beef. We have further found that this treatment prevents the development of off-flavors at sterilizing dosages of about 2-5 megarads.

Accordingly, it is a primary object of our invention to provide a simple and efiicient process used in conjunction with conventional irradiation sterilization procedures, which will remove the oif-fiavors in irradiated beef.

Another object of our invention is an efiective process which can be carried out without the use of gaseous chemicals, and at irradiation dosages sufficiently high to sterilize the beef.

A a further object of the invention is the provision of taste-acceptable irradiation-sterilized beef of high storage stability and free from wet dog. and similar irradiation induced cit-flavors.

Further objects and advantages will appear more particularly from the following description of specific examples by which our invention is carried into practice.

Exa mple 1 Beef, canning grade, was cooked for two hours in a closed kettle (pressure cooker) at 240 F. water temperature, then chilled, sliced, covered with an aqueous salt solution of .85-9% strength, placed in =1-pound cans and vacuum-sealed. The canned samples were submitted in two lots to gamma ionizing radiation from spent U reactor fuel rods containing gamma ray emitting fission products; Lot No. 1, 2 megarads (dose rate 1.28 megarads per hour; exposure time 1 hour 34 minutes); Lot No. 2, 4

3,093,489 Patented June 11, 1963 megarads (dose rate 1.29 megarads per hour; exposure time 1 hour 6 minutes). Irradiation was accomplished at the Argonne Gamma Irradiation Facility oi the'U.S. Atomic Energy Commission.

The cans of both lots were stored for 6 months, then opened, and the saline solution discarded prior to serving the beef slices to a taste panel. Reconstituted beef gravy was added to the irradiated beef to approximate the beef and gravy controls. The taste panel compared the samples with unirnadiated beef and gravity controls, that were heat-processed and vacuum canned by conventional procedures. The taste acceptability score of Lot No. 1 exceeded that of the control substantially, while that of Lot No. 2 was about the same as that of the control.

Example 2 Example 1 was repeated at irradiation dosages of 3 and 5 megarad-s, respectively. The taste acceptability of the 3 megarad sample was about the same as that of Lot No. l in the preceding example, and the taste acceptability of the 5 megarad sample was about the same of Lot No. 2 of the preceding example.

The absence of the wet dog and other off-flavors was noted in all irradiated lots of Examples 1 and 2.

Example 3 Example 2 was repeated with an aqueous salt solution of 4.25% strength at irradiation dosages of 3 and 5 meg- :arads. The taste acceptability of both lots (3 and 5 rnegarads irradiation) exceeded that of the unirradia-ted control sample, and no objectionable off-flavors were noted by the taste panel.

Among other suitable gamma ray sources is, e.g., cobalt 60.

In lieu of gamma radiation, ionizing radiation from a beta ray source, such as a Van de Graafr high energy electron accelerator of a capacity of .5, 1, 2 or more m.e.v., may be employed at corresponding dosages (e.g., 2 to 5 magarads).

Although we do not wish to be bound by any particular theory by which the beneficial eifect of our invention is to be explained, we postulate that most or all of the offflavors developed by ionizing irradiation of beef are of a water-soluble nature, and are thus susceptible to extraction from the irradiated beef by means of the surrounding water solution. The effect of any remaining oiidlavors in the beef is presumably neutralized by a slightly salty taste imparted to the beef by the saline solution, which gives it the taste of beef seasoned to the preference of the average consumer.

The termbeef as used in the specification and claims, denotes meat of the bovine genus (including veal).

Having thus explained the nature of our invention and illustrated its practice by several examples, we desire it to be understood that variations and departures of the operating conditions disclosed by us will readily appear to the expert, and are to be deemed within the scope of our invention and of the appended claims.

We claim:

1. Process for preventing off-flavors in radiation-sterilized beef, comprising surrounding said beef with an aqueous solution of sodium chloride prior to exposure of said beef to radiation, said solution having a strength of at least about .85%, exposing said beef, while surrounded by said solution, to a dose of ionizing radiation not exceeding about 5 megarads and suflicient to sterilize said beef, and then discarding said solution prior to serving said beef; whereby radiation-induced off-flavors are eluted from said beef and discarded with said solution.

2. Process according to claim 1, wherein said ionizing radiation is gamma radiation.

3. Process according to claim 1, wherein said radiation dose is about 2 to 5 megarads.

4. Process according to claim 2, wherein said radiation dose is about 2 to 5 megarads.

5. Process according to claim 1, wherein the strength of said solution is about .854.25%.

6. Process of preventing off-flavors in radiation-sterilized beef, comprising surrounding said beef with an aqueous solution of sodium chlonide prior to exposure of said beef to radiation, said solution having a strength of about .854.25%, sterilizing said beef, while surrounded by said solution, by means of ionizing radiation of 10 2 832 689 4 about 2 to 5 megarads, and then discarding said solution prior to serving said beef; whereby radiation-induced olfflavors are eluted from saidbeef and discarded with said solution.

7. Process according to claim 6, wherein said ionizing radiation is gamma radiation.

References Cited in the file of this patent UNITED STATES PATENTS Proctor et a1. Apr. 29, 1958 

1. PROCESS FOR PREVENTING OFF-FLAVOR IN RADIATION-STERILIZED BEEF, COMPRISING SORROUNDING SAID BEEF WITH AN AQUEOUS SOLUTION OF SODIUM CHLORIDE PRIOR TO EXPOSURE OF SAID BEEF TO RADIATION, SAID SOLUTION HAVING A STRENGTH OF AT LEAST ABOUT .85%, EXPOSING SAID BEEF, WHILE SURROUDED BY SAID SOLUTION, TO A DOSE OF IONIZING RADIATION NOT EXCEEDING ABOUT 5 MEGARDS AND SUFFICIENT TO STERILIZE SAID BEEF, AND THEN DISCARDING SAID SOLUTION PRIOR TO SERVING SAID BEEF; WHEREBY RADIATION-INDUCED OFF-FLAVORS ARE ELUTED FROM SAID BEEF AND DISCARDED WITH SAID SOLUTION. 